Integrated circuits find application in many of today's consumer electronics, such as cell phones, video cameras, portable music players, printers, computers, etc. Integrated circuits may include a combination of active devices, passive devices and their interconnections.
Mixed-signal, logic and RF integrated circuits often contain resistors to exert a desired control over current in a particular part of an electronic circuit. To achieve a particular resistance value within a resistor, a circuit designer typically modifies the length and/or width of the resistor material because, as is well known in the art, resistance is directly related to the length of the resistor and inversely related to the width of the resistor. Moreover, it is desirable to manufacture the resistor from a material with a high sheet resistance value because resistance is directly related to sheet resistance. Fortunately, for the semiconductor industry intrinsic silicon, which possesses a resistivity of about 2.5×105 ohms-cm, can be altered through the introduction of dopants to obtain a desired resistivity or conductivity.
Accordingly, extrinsic poly-silicon is typically used to form resistors, not only because the resistivity of the resistor can be precisely controlled by introducing dopants, but also because resistors can be concurrently formed from the same poly-silicon layer that forms the gate structures of adjacent active devices. Unfortunately, concurrent formation requires additional special process steps to alter the resistivity of the resistor, such as shallow implants with reduced doping concentration and reduced thermal budgets. However, these special process steps inevitably degrade the poly-depletion effect and transistor performance.
Thus, a need still remains for a reliable integrated circuit system and method of fabrication, wherein the integrated circuit system includes a high resistance resistor without degrading transistor performance. In view of the ever-increasing commercial competitive pressures, increasing consumer expectations, and diminishing opportunities for meaningful product differentiation in the marketplace, it is increasingly critical that answers be found to these problems. Moreover, the ever-increasing need to save costs, improve efficiencies, and meet such competitive pressures adds even greater urgency to the critical necessity that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.